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SqlFriend
Starting Member
26 Posts |
 Posted - 2004-09-01 : 16:47:42
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| I have these sets of data I will call "files" for the purpose of this note. I want users to be able to "check out" files and then no one else can modify them while this user has it. When they are done modifying it, they check it back in.How would you handle this? Is there a test and set method which occurs in a unary way I could do on a column?How would you handle if a user checked out something and then did nothing with it for an extended period.. would you automatically check it back in? Allow for someone else to "steal" the checkout after a day? And then what if after that day passes the user decides to actually check in the changes? |
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DustinMichaels
Constraint Violating Yak Guru
464 Posts |
Posted - 2004-09-01 : 16:52:58
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| You could have a column indicating if the item is checked out and the date/time it was checked out.If the user has the item for to long you could use the date/time attribute of the record to determine if the user's lock should be broken.Dustin Michaels |
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SqlFriend
Starting Member
26 Posts |
Posted - 2004-09-01 : 17:03:33
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| I like that idea- but what if two people set it at the same moment?I guess you could have them update where primary key matches and also checked out = false- then look at the result and see if they actually got it |
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DustinMichaels
Constraint Violating Yak Guru
464 Posts |
Posted - 2004-09-01 : 17:54:03
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If two people try to update it at the same time then you have to trust sql server to make sure only one person gets exclusive control of the item. If you need to you may need to put a lock on the table if your paranoid  Dustin Michaels |
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X002548
Not Just a Number
15586 Posts |
Posted - 2004-09-01 : 18:32:31
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| You need an Update datetime column...and possibly an update by to know whoAnd in one trans, check then datetime, and if it less than the time you got the data, then update, else return the data of the updated row....Or not....and let fate decide....You need to think about overhead....Brett8-) |
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Preventing two users changing